Electromagnetic signal.



No. 840,201. PATENTED JAN. 1, 190? HW M. CRANE. v ELECTROMAGNETIC SIGNAL.

APPLICATION FILED JUNE 8, 1904.

No. 840,201. PATENTED JAN. 1, 1907.

H. M. CRANE. ELECTROMAGNETIC SIGNAL.

ED JUNE 8, 1904.

v citizen of the United States, residing at New UNITED STATES PATENT OFFICE.

HENRY M. CRANE, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTROMAGNETIC SIGNAL.

Specification of Letters Patent.

rammed Jan. 1, 1907.

Application filed June 8, 1904. Serial No. 211,611.

To all whom it may concern:

Be it known that ,I, HENRY M. CRANE, a

York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Electromagnetic Signals, (Case No. 12,) of which the following is a full, clear, concise, and exact description.

My invention relates to an electromag netic annunciator-drop, and has for its object to provide an improved device which will be compact and so constructed that the signal may not be operated if the annunciator is accidentally jarred or shaken.

I will describe my invention by reference to the accompanying drawings. H

Fi ure 1 is a view in elevation of my annunclator-drop. Fig. 2 is a vertical sectional view thereof. ig. 3 is an end view. Fig. 4 is a detail view of the target and its supporting-arm. Fig. 5 is a view in elevation of a modified form of my invention.

. Fig. 6 is a vertical sectional view thereof, and

Fig. 7 is an end view.

The same letters of reference are used to designate the same parts Wherever shown. Referring first to Figs. 1 to 4, inclusive, the electromagnet 6, comprising a core b, polepiece b and helixb, is mounted upon a plate a, adapi ted to be secured to a suitable support 0. he core is provided with a projecting end or extension upon which is centrally pivoted an armature e. Said extension is of reduced cross-section and adapted to enter a hole in the armature e, a pin passing through said armature and extension to form a pivot for said armature. A sleeve d, of non-magnetic metal, is preferably provided for the projecting end of said core in order to prevent sticking or freezing of the armature to said core, due to magnetic fr1ction between the armature and the core upon which it is pivoted. The upper end of the armature e is connected by a retractile spring f with the plate a, a stop g preferably passing through the upper end of the armature to engage the insulating-head of the magnet-spool and limit the movement of the armature. The, lower end of the armature is presented before the end of the L-shaped pole-piece,'secured to the rear of the magnet-core, which may be provided with a nonmagnetic shield, as shown, to prevent sticking of the armature. The electromagnet b may be considered as a U-shaped magnet, the core I) and pole-piece b forming the arms thereof. A lever-arm 'h is pivoted to the plate a and carries a target it, an opening h being provided in said arm, through which the lower end of the armature may pass, the edge of the opening riding up over the end of said armature (which is preferably beveled) and into a transverse groove e in the face of the armature, which groove serves at a latch to hold the arm in the position indicated.

Referring to Figs. 5 to 7, inclusive, which illustrate a modified form of my invention, the armature e is centrally pivoted upon the pole piece or arm I) of the magnet, with its lower end presented before the end of the core I), which may be providedwith a non-magnetic shield to prevent sticking of the armature. The lower end of the armature normally rests against a stop I), which limits its outward movement, said stop being carried by a pin secured tothe core I) and passing through a hole in the armature. The upper end of the armature e when the same is unattracted is adapted to engage the lever arm 72. tomaintain the same in the position indicated, said armature being moved and held in such position by the retractile spring f; but when the armature is moved by the energization of magnet b the upper end of the armature registers with the opening h in said arm, allowing the arm to fall into its alternative position, as shown in dotted lines in Fig. 5. It will thus be seen that when the lever-arm is in its upper position and held by the armature the retractile spring acts upon the armature in such a way as to tend to hold the same in firm engagement with the leverarm, so that a positive attraction of the armature is required to release the lever-arm. The armature being pivoted at or approximately at its center of gravity, the force of any jar or blow is exerted equally upon both sides of the pivotal joint and causes no movement of the armature to release the target.

I claim+ In an annunciator-drop, the combination with an electromagnet having a projecting core, of a return pole-piece for said magnet, a

supporting-plate for said magnet, an armaend of said armature with saidiglaite, a stop V In witness whereof I hege unt0 subscribecarried by the upper end of 35nd armature my name this'llth day of April, A. D. 1904.-

adapted to abut against said magnet to limit the retractive movement of said armature 5 and a target-arm fiivoted to said plate and i Witnesses:

normally held by-t other end of said arma- H. B. GILMORE, ture. .J. C. Emmng. 

